My Feed is not generated automatically

1) Is the extension enabled in the default configuration scope?
Check if it is enabled. It will be in Admin -> System -> Configuration -> Extensionname-> Enabled.
If you are running multiple websites within one installation and only wish to use the extension in one, always enable the extension in the default configuration scope and overwrite this in the other stores by setting "Enabled" to "No" on the store level. A cron always runs in the global scope.

3) Are the Feeds generated manually?
Check if the feeds can be successfully generated manually. The feed must be successfully generated manually whenever you activate the cronjob functionality.

3) Have you enabled the Feed Generation & Cronjob?
Check if you have enabled the feed generation function, including the cronjob functionality which can be found in System -> Config -> Extension -> Feed Generation Settings.

4) How to check if the Magento cron is setup correctly
?
Magento depends heavily on its cron. As of Magento EE 1.14.1 and Magento CE 1.9.1 all Magento e-mails (including order confirmation and transactional) are sent by cron.

It's also used for tasks as: DB log cleanups, sending newsletters, generating Google Sitemaps, etc. However, many people forget to set up this cron.

You can check if the cron is running by checking the the cronjob timeline using the AOE Scheduler extensions. With this extension you can manage, view and test your scheduler/cron tasks including a timeline. You can download this extension right here.

With the AOE scheduler extension it's possible to get a timeline view of all the available cronjob tasks. It scans the xml configuration from Magento and your additional extension (including our extension) and generates a list of all tasks, while also considering those tasks, whose intervals can be configured dynamically within the Magento backend (e.g. sitemap generation). You can also choose to run the task directly. Be careful with that, as the execution might last longer than a few seconds or might depend on some other command line environment settings. For testing small tasks this might still be a safer option.

After installation, navigate in the admin to Systeem > Scheduler > List View. Sort this tabel on Status > Success to check if there are jobs that have run successfully. Also in this screen you will see a notice of the heartbeat of the cron is running.

If there are no successful runs, this means that you have not setup the Magento cron. Please ask you hosting provider to fix this. You can find this information under System > Scheduler > Instructions.

Please note that setting up a Magento cron is part of the
Magento installation & configuration.